ace supplied by a second row of petals, within which is a third series
of petals, representing, says M. de Candolle, the inner row of stamens
that theory suggests should exist in the natural condition. Moreover,
the carpels in this variety are five in number instead of three. In
_Erica Tetralix_ the corolla may not unfrequently be found divided to
the base into its constituent petals, and the place of the stamens
occupied by a series of petal-like structures entirely destitute of
anther.

In monocotyledonous flowers, especially those with a coloured perianth,
the substitution of segments of the perianth for stamens occurs not
unfrequently. M. Seringe has observed this in the stamens of _Lilium
Martagon_, and there is in cultivation a variety of the white lily,
_Lilium candidum_, sometimes called the double white lily, in which the
segments of the perianth, in place of being arranged in two rows, are
greatly increased in number, and disposed in a spiral manner. In these
flowers, not only are the stamens and pistils thus modified, but also
the upper leaves of the stem. In so-called double tulips there is
likewise a replacement of stamens by coloured segments of the perianth,
but this happens generally in connection with an increase in the number
of organs. Moquin-Tandon remarks having seen in a garden in the environs
of Montpelier a tulip, the stamens of which showed all possible stages
of transition between the form proper to them and that of the perianth.
The pistil in this case was transformed into several small leaves.
Similar appearances have been observed in Iris, Hyacinths, Narcissus,
Colchicum, and Crocus. M. Fournier[300] describes a flower of _Narcissus
Tazetta_ from within the normal perianth of which sprang a second one,
equally provided with a cup and occupying the space usually filled by
the stamens. Flowers of _Narcissus poeticus_ may also be met with in
which the stamens are replaced by six distinct segments exactly
resembling those of the perianth in miniature.[301]

[Illustration: FIG. 154.--Double columbine, _Aquilegia_--petalody of the
filament.]

From an examination of these flowers it becomes evident that
petalification is brought about in different flowers in different ways;
sometimes it is the filament which becomes petaloid, sometimes the
anther-lobes, while at other times it is the connective which assumes
the appearance of petals.[302] For instance, in _Solanum tuberosum_,
_S. Dulcamara_, in